Resistor Calculator Color Code

Resistor Value Formula:

\[ R = (band1 \times 10 + band2) \times 10^{band3} \]

Band 1 (1st Digit):

Band 2 (2nd Digit):

Band 3 (Multiplier):

Resistor Value:

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is a Resistor Color Code Calculator?

Definition: This calculator determines the resistance value of a resistor based on its color bands.

Purpose: It helps electronics engineers, technicians, and hobbyists quickly identify resistor values without memorizing the color code.

2. How Does the Calculator Work?

The calculator uses the standard color code formula:

\[ R = (band1 \times 10 + band2) \times 10^{band3} \]

Where:

\( R \) — Resistance value (ohms)
\( band1 \) — First significant digit (1st color band)
\( band2 \) — Second significant digit (2nd color band)
\( band3 \) — Multiplier/exponent (3rd color band)

Explanation: The first two bands represent digits, the third band is the power-of-ten multiplier.

3. Importance of Resistor Color Codes

Details: Color coding is the standard method for marking resistor values on small components where printed numbers would be impractical.

4. Using the Calculator

Tips: Select the color for each band from the dropdown menus. The calculator automatically converts the result to ohms (Ω), kilohms (kΩ), or megohms (MΩ) as appropriate.

5. Frequently Asked Questions (FAQ)

Q1: What about 4-band and 5-band resistors?
A: This calculator handles standard 3-band resistors. For 4-band resistors, the first three bands work the same way (two digits + multiplier), and the fourth band indicates tolerance.

Q2: Why are gold and silver in the multiplier band?
A: Gold represents ×0.1 (10^-1) and silver represents ×0.01 (10^-2), used for very small resistance values.

Q3: How accurate are color-coded resistors?
A: Accuracy depends on the tolerance band (not included in this calculator). Standard resistors are typically ±5% (gold) or ±10% (silver).

Q4: What if my resistor has more bands?
A: Additional bands usually indicate tolerance (4th band) and temperature coefficient (5th band). The first three bands always indicate the significant digits and multiplier.

Q5: Can I use this for surface mount resistors?
A: No, SMD resistors use a different numbering system. This calculator is only for through-hole resistors with color bands.